Glass fiberboards for vacuum heat insulation have excellent long-term durability of 15 years or more and excellent initial thermal conductivity of 3.0 mW/mk or less at a size of 600×600 mm
Generally, glass fiberboards are produced by mixing micro-glass fibers and general glass fibers in a ratio of 6:4 to 9:1, stirring in a solution of pH 2˜4, and drying the mixture in the form of a board. Upon stirring, the micro-glass fibers are twisted, thereby facilitating production of the glass fiberboard while providing excellent heat insulation performance.
On the other hand, micro-glass fibers having a diameter of 1˜3 μm are produced by a flame process, which cause environmental pollution and often suffers poor quality causing significant increase in manufacturing costs. Due to such disadvantages, the production of micro-glass fibers is only allowed in some countries, and regulations concerning treatment of glass fibers having a diameter of 4 μm or less are enforced in Europe due to concerns regarding human heath.
Therefore, there is a need for development of a core material for vacuum heat insulation with standardized glass fibers having a diameter of 4 μm or more.
To produce a board using standardized glass fibers, a binder is used. Glass fibers having a diameter of 4 μm or more have a linear shape and thus do not entail a twisting phenomenon unlike micro-glass fibers.
In use of a general inorganic binder, movement of moisture causes the binder to move in the course of drying, whereby only the surface can be cured, thereby causing deterioration in heat insulation performance.
Therefore, there is a need for the provision of a glass fiberboard through application of an optimized inorganic binder to standardized glass fibers such that the binder and the glass fibers can be uniformly distributed even after drying.